package com.ysh.contentcenter.configuration;

import com.alibaba.nacos.api.exception.NacosException;
import com.alibaba.nacos.api.naming.NamingService;
import com.alibaba.nacos.api.naming.pojo.Instance;
import com.alibaba.nacos.client.naming.core.Balancer;
import com.netflix.client.config.IClientConfig;
import com.netflix.loadbalancer.AbstractLoadBalancerRule;
import com.netflix.loadbalancer.BaseLoadBalancer;
import com.netflix.loadbalancer.Server;
import lombok.extern.slf4j.Slf4j;
import org.springframework.cloud.alibaba.nacos.NacosDiscoveryProperties;
import org.springframework.cloud.alibaba.nacos.ribbon.NacosServer;
import org.springframework.util.CollectionUtils;

import javax.annotation.Resource;
import java.util.ArrayList;
import java.util.List;
import java.util.Objects;
import java.util.stream.Collectors;

@Slf4j
public class NacosSameClusterWeightedRule extends AbstractLoadBalancerRule {

    @Resource
    private NacosDiscoveryProperties nacosDiscoveryProperties;

    @Override
    public void initWithNiwsConfig(IClientConfig iClientConfig) {

    }

    @Override
    public Server choose(Object o) {
        try {
            // 拿到配置文件中的集群名称
            String clusterName = nacosDiscoveryProperties.getClusterName();
            BaseLoadBalancer loadBalancer = (BaseLoadBalancer) this.getLoadBalancer();
            // 想要请求的微服务的名称
            String name = loadBalancer.getName();
            // 拿到服务发现的相关API
            NamingService namingService = nacosDiscoveryProperties.namingServiceInstance();
            // 后面的参数是是否只拿健康的实列 这里是获取指定服务的所有实例
            List<Instance> instances = namingService.selectInstances(name, true);
            // 过滤出相同集群下的所有实例
            List<Instance> sameClusterInstances = instances.stream().filter(instance -> Objects.equals(instance.getClusterName(), clusterName)).collect(Collectors.toList());
            // 如果同一个集群下没有实例的话 就使用之前查出来的instances
            List<Instance> instancesToBeChosen=new ArrayList<>();
            if(CollectionUtils.isEmpty(sameClusterInstances)){
                instancesToBeChosen=instances;
                log.warn("发生跨集群调用，name={},clusterName={},instances={}",name,clusterName,instances);
            }else{
                instancesToBeChosen=sameClusterInstances;
            }
            // 基于权重的负载均衡算法返回一个实例
            Instance instance = ExtendBalancer.getHostByRandomWeight2(instancesToBeChosen);
            log.info("选择的实例是 port:{},instance:{}",instance.getPort(),instance);
            return new NacosServer(instance);
        } catch (NacosException e) {
            log.error("发生异常了",e);
            return null;
        }
    }
}

class ExtendBalancer extends Balancer{
    public static Instance getHostByRandomWeight2(List<Instance> hosts){
        return getHostByRandomWeight(hosts);
    }
}
